ARM: sun7i: dt: Add ahci / sata support

This patch adds sunxi sata support to A20 boards that have such a connector.
Some boards also feature a regulator via a GPIO and support for this is also
added.

Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>